Jason Peter Rochford admitted in his letter to a judge that his thefts of donation boxes were "about as low as you can go".

The unemployed 27-year-old, from Addington, has been jailed for 18 months for a series of thefts.

He owes $19,000 to the court system, but $17,975 is unpaid reparations from previous offending.

He pleaded guilty to 13 charges, and defence counsel Claire Yardley said he was under no misapprehension at his Christchurch District Court sentencing by Judge Raoul Neave that a prison term would be imposed.

Yardley said Rochford acknowledged that he had a serious drug problem and hoped that he could get help for his addiction during his sentence or as part of his release.

He had already served several jail terms but found that after his release it took so long to obtain any rehabilitation assistance that he was already back in trouble.

He acknowledged in his letter to the judge that the donation thefts were "about as low as you can go".

Judge Neave said the thefts of donation boxes from the Earthquake Recovery Appeal and the Returned and Services' Association were "particularly mean" and added time to Rochford's sentence because of them.

He said the 13 thefts involved reparation of $6000 but he made no order because there was no hope he would be able to repay the money.

He noted Rochford had 51 previous convictions for dishonesty.

The letter to the court indicated Rochford was ashamed of his actions and realised he had humiliated his family.

Many of the thefts were from small retailers who could not afford the losses.

Rochford's letter was also a plea for assistance to get rehabilitation but there was no bed available at the Odyssey House programme at present and that option was not available to the judge.

He imposed sentences totalling 18 months, with six months of release conditions, and said he would allow Rochford to apply to substitute the sentence for home detention if a place at Odyssey House became available.